High-speed network impairment instruments contain a small, fixed number of packet classifiers in order to classify packets based on their contents. These packet classifiers match and isolate relevant data flows. In an impairment instrument, these data flows are subjected to different kinds of impairment, such as adding delay to a flow or randomly dropping packets from a flow, in order to emulate the behavior of a Wide Area Network link.
The user provides configuration data to set up each packet classifier. If the user makes an error in configuring the classifier, and the wrong packets are classified or no packets are classified due to the configuration error, impairment functions of the instrument will either be invoked unnecessarily or not invoked when they should be. In addition, such configuration errors may not be immediately discoverable as the user is required to search through packet classification results to determine the effects of the filter configuration.
In light of these disadvantages, there exists a need to show the user a preview of the packets matching the current classifier configuration, while they are changing the configuration.